Yes, use type=twolevel and estimator=wlsmv. It might be helpful to look at example 9.9 in the users guide (except you won't have a between level factor). You can also take a look at this paper and the simulation study in section 5. http://statmodel.com/download/p2t1.pdf

I think you are running into the problem of too many dimensions of integration. With ML, you should fix the residual variances to zero, u1-u10@0; If you don't, each one requires one dimension of integration.

The notion of item-specific random effects is interesting but I want a single random effect for the item difficulties. This model is described, for example, by Van den Noortgate, W., De Boeck, P., & Meulders, M. (2003). Cross-classification multilevel logistic models in psychometrics. Journal of Educational and Behavioral Statistics, 28, 369–386.